Without trying to confuse you further, I think you've gotten to the point of differentiating between the s100 and the Elph 110.

There is also a relatively new Powershot s110 which is not related to the ELPH.

The s110 is essentially and updated version of the s100. Both have a relatively large sensor of 12.1 megapixels, manual or automated controls, RAW as well as JPG and a bunch of other features, including two I find useful. GPS and WIFI transfer. The s100 has GPS but not wifi.

They are both enthusiasts cameras and mine serves a walkabout backup to my 5D Mark III. It is very capable. The s100 and s110 have many specs in common with the G15- sensors, etc. The lens is different and the G15 does not have GPS.

I could go for either the s100 or s110 power shots.

As it is, I've owned the s90, a slightly earlier version and the s100.

Re Megapixels, not all megapixels are created equal. Those are very solid 12.1 megapixels.

Actually, not that it matters much but I believe that the S110 does NOT have GPS. It can integrate a GPS position from a linked smartphone, but it doesn't have it's own GPS. I say "not that it matters much" because IMO one of the weak points of the S100 is the short battery life... so to maximize the number of shots I can get on a battery I usually leave the GPS off (and if I had an S110 and wanted the GPS info tagged onto the photos I'd link it to my phone). But just for accuracy's sake I thought I'd point out that the S110 dropped that feature and replaced it with wifi.